ASHINGTON, Dec. 23  Pentagon officials said today that Americans in some
areas of the country could expect to see more warplanes in the skies during
the holiday season now that a higher antiterrorism alert level is in effect.

"They may see additional air patrols over select cities and facilities,
an increase in the air-defense posture here in Washington, D.C., and combat
aircraft could be put on a higher alert at different air bases throughout the
country," the chairman of the Joint Chiefs of Staff, Gen. Richard B. Myers,
said at a Pentagon briefing.

"We have dedicated people and resources available to protect our citizens,
and we are taking some of those precautions today," the general added.

Defense Secretary Donald H. Rumsfeld and General Myers reiterated the Bush
administration's message to the American people: the heightened alert, to orange
from yellow, was based on credible and specific information, but that people
should not let caution dissolve into panic.

"We're free people," Mr. Rumsfeld said. "We shouldn't sit around
hiding under chairs. We have to live our lives."

Mr. Rumsfeld and General Myers also indicated, without saying so outright,
that the Pentagon wanted to continue vaccinating service members against anthrax,
despite a federal judge's decision on Monday that the military could not compel
members of the armed forces to do so.

Mr. Rumsfeld said Pentagon lawyers were studying the judge's decision and had
made no decision yet on an appeal. But Mr. Rumsfeld made no effort to hide his
displeasure at a passage in the decision that said members of the armed forces
could not be used as "guinea pigs."

"The comment, if in fact the judge said, is inaccurate," Mr. Rumsfeld
said crisply.

General Myers emphasized that the military leaders believe that vaccinations
are "extremely important" in protecting American troops, and he disputed
any suggestion that the inoculations are experimental. "We're using a vaccine
that has been around for 40 years," he said.

In announcing the elevated national alert level, to the second-highest position,
the secretary of homeland security, Tom Ridge, said last weekend that intelligence
analysts had detected signs that Al Qaeda terrorists might be hoping to soon
duplicate or surpass the attacks on Sept. 11, 2001, possibly again using hijacked
aircraft.

Mr. Rumsfeld and General Myers were walking the same tightrope today that they
and other top officials have had to negotiate several times in recent months:
warning people to be alert and cautious because of the information indicating
the possibility of imminent terror attacks, yet also urging them not to let
those threats steer their lives.

Asked if people should regard the higher threat level as "truly serious,"
Mr. Rumsfeld said they should. He also noted that the higher alert level triggers
more activity in law enforcement agencies at every level, and hence costs enormous
amounts of money.

"Therefore, you don't do it lightly," he said. "Is it serious?
You bet your life."

As he has many times, Mr. Rumsfeld struck a note of determination while cautioning
Americans not to expect victory in the campaign against terrorism anytime soon.
The effort "is not going to end with a surrender on the U.S.S. Missouri,"
he said, alluding to Japan's capitulation at the end of World War II. "If
we want to live as free people, we simply have to find the terrorists,"
he said, "and capture or kill them."